Chapter 9
9.1: Interpreting Quartiles and Interquartile Range
Objective…
Key Vocabulary…
Measure of Variation
First Quartile
Second Quartile
Third Quartile
Range
Interquartile Range
Part A: Introduce the Concept Of Measures of Variation
•
Heights of some of the players on two football teams
Red Team
Yellow Team
73
76
75
70
76
82
78
77
78
75
•
Calculate the Mean of both teams.
o Red: ____________________
o Yellow: ____________________
Chapter 9
9.1: Interpreting Quartiles and Interquartile Range
Part B: Understand Range
•
Use the above information and Calculate the Range of both teams:
o Red: ____________________
o Yellow: ____________________
•
Which team had a larger spread of heights? __________________
• Which team had a more consistent spread of heights? ___________
Practice…
1)
Find the range of history test scores of 10 students: 68, 73, 64, 70, 86,
54, 66, 89, 82, and 60.
2)
The table shows the average monthly temperatures in degrees
Fahrenheit in New York. Find the range of these temperatures.
Part C: Understand Quartiles
Lets think together…
• What’s the root word for quartiles?
•
How many groups may we separate the data into?
•
How do we find quartiles?
Chapter 9
9.1: Interpreting Quartiles and Interquartile Range
Consider the data values: 23, 28, 16, 11, 30, 21, 46, 55, 38, 37, 44, and 17
Process…
Steps Action
1
2
3
4
5
•
What’s the 5 Number Summary?
Practice…
1)
The data below shows body weights, in pounds, recorded at a health
screening of a group of people.
Find the 5 Number Summary and Graph it!
Min
Q1
Q2/Median
Q3
Max
Chapter 9
9.1: Interpreting Quartiles and Interquartile Range
2)
The heights, in centimeters, of the tomato seedling plants in a
greenhouse are listed below.
Find the 5 Number Summary and Graph it!
Min
Q1
Q2/Median
Q3
Max
Part D: Understand Interquartile Range
Let’s think together…
• What’s interquartile range?
Fifteen people were surveyed to find out how many hours they sleep every day.
The finds were as follows: 8, 8.4, 10, 6.5, 7.4, 9.5, 5, 7, 8, 11, 6, 8, 7.2, 11.5, 7
• Find the 5-Number Summary, Range, and Interquartile Range. Graph it!
Min
Q1
Q2/Median
Q3
Max
Chapter 9
9.1: Interpreting Quartiles and Interquartile Range
Practice…
1)
Out of 50 multiple-choice questions, 19 students scored the following number of
correct answers. Find the 5 number summary, range, and interquartile range.
Min
Q1
Q2/Median
Q3
Max
2)
Concert tickets were priced at $100, $70, $60, and $45. Twenty-two tickets
were sold in the first hour of sales. The table shows how many of each type of
ticket were sold. Find the 5 Number summary, range, and interquartile range.
Min
Q1
Q2/Median
Q3
Max
Chapter 9
9.1: Interpreting Quartiles and Interquartile Range
3)
A survey of 50 people asking the number of books they read in a year
produced the follow results. Find the 5 number summary, range, and
interquartile range.
Min
Q1
Q2/Median
Q3
Max